LENGTH OF A DEGREE 21 



then the ratio, in the Atlantic area, between the dis- 

 tance indicated in these charts and that based on 

 modern maps would be as .369 to 425, or .868. It 

 follows that, if the distance, expressed in degrees, be- 

 tween Land's End and the Strait of Gibraltar were the 

 same in each case, the scale of statute miles to the de- 

 gree would be reduced from 69 to 59.89, or (59.89 x 

 ^ = ) 65.1 Italian nautical miles. However, as 

 indicated above, the actual difference is 14° 20', 

 whereas the Ptolemy maps of 1490 of England and 

 Spain^^ show a difference of 16° 23 ' . This would 

 reduce the calculation in the proportion of 14° 20' 

 to 16"^ 23 ', or .874, bringing the estimate of Italian 

 nautical miles to the degree to 56.89 — again a close 

 approximation to 56 ^x'. 



While calling attention to the fact that there was an 

 error in the navigation charts, Columbus does not 

 state what in his judgment the nature of this error 

 might be. The comment which he makes (note 

 VII, above) refers, however, to a passage in which 

 the estimate of 56^ miles is attributed to Alfraganus. 

 It is not improbable, therefore, that Columbus had 

 reference to the difference which has just been pointed 

 out. If so, there was no escaping the conclusion, 

 if the Mediterranean scale was correct and if the lati- 

 tudes were correct, that 56^ miles represented a 

 close approximation to the length of a degree. 



" Nordenskiold, Facsimile- Atlas, PL 2: Bolerium Promot. (Land's 

 End), 52° 30'; PI. 3 (our Fig. i): northern coast of Strait of Gibraltar, 

 36° 7'. 



